#include "paint.h"

typedef void Op(Widget *, Mousectl *, int);
static Op tlcorner,	tedge,	trcorner;
static Op ledge,	move,	redge;
static Op blcorner,	bedge,	brcorner;
static Op sweep;

typedef struct State {
	Cursor	*c;
	Op	*f;
} State;

static State statetab[] = {
	{&topleft, tlcorner},	{&top, tedge},	{&topright, trcorner},	{&cross, sweep},
	{&left, ledge},	{&box, move},	{&right, redge},	{&cross, sweep},
	{&bottomleft, blcorner},	{&bottom, bedge},	{&bottomright, brcorner},	{&cross, sweep},
	{&cross, sweep},	{&cross, sweep},	{&cross, sweep},	{&cross, sweep},
};

static int
region1(int m, int emin, int emax, int om, int im)
{
	if(m < emin - om)
		return 3;
	if(m <= emin + im)
		return 0;
	if(m < emax - im)
		return 1;
	if(m <= emax + om)
		return 2;
	return 3;
}

static State *
regionstate(Point m, Rectangle r)
{
	enum { om = 8 };
	int imx, imy, reg;

	/* calculate the interior margins so that there is at least an
	8*8 space for the center region */
	imx = clampint(0, (r.max.x - r.min.x - om) / 2, om);
	imy = clampint(0, (r.max.y - r.min.y - om) / 2, om);

	reg = region1(m.x, r.min.x, r.max.x, om, imx);
	reg |= region1(m.y, r.min.y, r.max.y, om, imy) << 2;
	return &statetab[reg];
}

static void
sweep(Widget *w, Mousectl *mctl, int but)
{
	Canvas *c;
	Rectangle r;
	Point p, q;

	c = w->aux;
	c->sel.active = 0;
	p = mctl->xy;
	do {
		q = mctl->xy;
		r = clamprect(stomrect(canonrect(Rpt(p, q)), w), c->s->mem->r);
		w->redraw(w, RDall);
		antsrect(w->screen, w->r, mtosrect(r, w));
		readmouse(mctl);
	} while((mctl->buttons & 7) == but);

	if(mctl->buttons == 0) {
		if(c->sel.active = !eqpt(p, q))
			c->sel.r = r;
	}
}

static void
move(Widget *w, Mousectl *mctl, int but)
{
	Canvas *c;
	Point m;	/* the position of the mouse within the selection */
	Rectangle s;	/* the area of the selection relative to 0,0 */
	Point p;	/* the location of the new selection on the image */

	c = w->aux;
	s = rectsubpt(c->sel.r, c->sel.r.min);
	c->sel.active = 0;
	m = subpt(stompt(mctl->xy, w), c->sel.r.min);
	do {
		p = subpt(stompt(mctl->xy, w), m);
		w->redraw(w, RDall);
		antsrect(w->screen, w->r, mtosrect(rectaddpt(s, p), w));
		readmouse(mctl);
	} while((mctl->buttons & 7) == but);

	if(mctl->buttons == 0) {
		c->sel.r = rectaddpt(s, p);
		c->sel.active = 1;
	}
}

#define EDGE(NAME, DIM, PT)	\
static void	\
NAME(Widget *w, Mousectl *mctl, int but)	\
{	\
	Canvas *c;	\
	Point itmp;	\
	Rectangle s, r;	\
	int m;	/* the position of the mouse relative to the edge */	\
	\
	c = w->aux;	\
	s = c->sel.r;	\
	itmp = stompt(mctl->xy, w);	\
	m = itmp.DIM - s.PT.DIM;	\
	c->sel.active = 0;	\
	do {	\
		itmp = stompt(mctl->xy, w);	\
		s.PT.DIM = itmp.DIM - m;	\
		r = clamprect(canonrect(s), c->s->mem->r);	\
		w->redraw(w, RDall);	\
		antsrect(w->screen, w->r, mtosrect(r, w));	\
		readmouse(mctl);	\
	} while((mctl->buttons & 7) == but);	\
	\
	if(mctl->buttons == 0) {	\
		c->sel.r = r;	\
		c->sel.active = 1;	\
	}	\
}	\

EDGE(tedge, y, min)
EDGE(bedge, y, max)
EDGE(ledge, x, min)
EDGE(redge, x, max)

#define CORNER(NAME, X, Y)	\
static void	\
NAME(Widget *w, Mousectl *mctl, int but)	\
{	\
	Canvas *c;	\
	Rectangle s, r;	\
	Point m;	/* the position of the mouse relative to the corner */	\
	Point p;	\
	\
	c = w->aux;	\
	s = c->sel.r;	\
	m = subpt(stompt(mctl->xy, w), Pt(X, Y));	\
	c->sel.active = 0;	\
	do {	\
		p = subpt(stompt(mctl->xy, w), m);	\
		X = p.x;	\
		Y = p.y;	\
		r = clamprect(canonrect(s), c->s->mem->r);	\
		w->redraw(w, RDall);	\
		antsrect(w->screen, w->r, mtosrect(r, w));	\
		readmouse(mctl);	\
	} while((mctl->buttons & 7) == but);	\
	\
	if(mctl->buttons == 0) {	\
		c->sel.r = r;	\
		c->sel.active = 1;	\
	}	\
}	\

CORNER(tlcorner, s.min.x, s.min.y)
CORNER(trcorner, s.max.x, s.min.y)
CORNER(blcorner, s.min.x, s.max.y)
CORNER(brcorner, s.max.x, s.max.y)

static int
mouse(Widget *w, Mousectl *mctl)
{
	Canvas *c;
	State *state;
	Point oldxy;
	Selection oldsel;

	c = w->aux;
	while(ptinrect(mctl->xy, w->r)) {
		state = c->sel.active ? regionstate(mctl->xy, mtosrect(c->sel.r, w)) : &statetab[3];
		fastsetcursor(mctl, state->c);

		if(mctl->buttons & 7) {
			oldxy = mctl->xy;
			oldsel = c->sel;
			state->f(w, mctl, mctl->buttons);
			if(mctl->buttons != 0) {
//				moveto(mctl, oldxy);
				c->sel = oldsel;
				w->redraw(w, RDall);
				while(mctl->buttons)
					readmouse(mctl);
			}
		} else {
			readmouse(mctl);
		}
	}

	fastsetcursor(mctl, nil);
	return 0;
}

CanvasTool rselect = {
	mouse,
};